telnet library https://docs.python.org/2/library/telnetlib.html

Paramiko, SSHv2 library http://docs.paramiko.org/en/2.2/

Netmiko library, multi vendor SSH client. https://github.com/ktbyers/netmiko

Napalm library, abstraction multi vendor support. Use nativ API when possible. Cisco IOS use Netmiko SSH library. Focus on managing configuration tasks. https://github.com/napalm-automation/napalm

pyntc library, multi vendor support. Use nativ API when possible. Cisco IOS use Netmiko SSH library. Focus on system level tasks. https://github.com/networktocode/pyntc